Core network selection method, apparatus and system

1. A method, comprising: obtaining, by a terminal, first network slice information from an access network device, wherein the first network slice information comprises information about at least one network slice; selecting, by the terminal, information about a to-be-accessed network slice from the first network slice information; and sending, by the terminal, the information about the to-be-accessed network slice to the access network device, wherein the information about the to-be-accessed network slice is used by the access network device to determine a core network device; wherein the first network slice information comprises at least one network slice type; wherein selecting, by the terminal, the information about the to-be-accessed network slice from the first network slice information comprises: selecting, by the terminal from the at least one network slice type, a network slice type which matches a service type of the terminal, as a type of the to-be-accessed network slice; and wherein sending, by the terminal, the information about the to-be-accessed network slice to the access network device comprises: sending, by the terminal, the type of the to-be-accessed network slice to the access network device, wherein the type of the to-be-accessed network slice is used by the access network device to determine the core network device.

2. The method according to claim 1 , wherein selecting the information about the to-be-accessed network slice from the first network slice information comprises: determining a to-be-accessed public land mobile network (PLMN) according to a first preset rule; and selecting, from the at least one network slice type, a network slice type which matches the service type of the terminal and is supported by the to-be-accessed PLMN, as the type of the to-be-accessed network slice.

3. The method according to claim 1 , wherein the first network slice information further comprises at least one network slice identity (ID) and a priority for each of the at least one network slice type; wherein selecting the information about the to-be-accessed network slice from the first network slice information comprises: when only one network slice type of the at least one network slice type matches the service type of the terminal, determining the only one network slice type as the type of the to-be-accessed network slice, or when multiple network slice types of the at least one network slice type match the service type of the terminal, selecting the type of the to-be-accessed network slice from the multiple network slice types according to the respective priority of each of the multiple network slice types; and wherein sending the information about the to-be-accessed network slice to the access network device, wherein the access network device determines the core network device according to the information about the to-be-accessed network slice, further comprises: sending the network slice ID of the to-be-accessed network slice to the access network device, wherein the network slice ID of the to-be-accessed network slice is used by the access network device to determine the core network device.

4. The method according to claim 1 , wherein before obtaining the first network slice information from the access network device, the method further comprises: sending a first message to the access network device, wherein the first message indicates a network slice selection capability of the terminal; and wherein obtaining the first network slice information from the access network device comprises: receiving a second message from the access network device according to the first message, wherein the second message comprises the first network slice information.

5. The method according to claim 4 , wherein before sending the information about the to-be-accessed network slice to the access network device, the method further comprises: requesting, to the access network device, to establish a wireless connection.

6. The method according to claim 1 , wherein the first network slice information further comprises at least one network slice ID and a priority for each of the at least one network slice type; wherein selecting the information about the to-be-accessed network slice from the first network slice information comprises: determining a to-be-accessed public land mobile network (PLMN) according to a first preset rule; selecting, from the at least one network slice, a network slice type which matches the service type of the terminal and is supported by the to-be-accessed PLMN; and when only one network slice type of the at least one network slice-type matches the service type of the terminal, determining the only one network slice type to be the type of the to-be-accessed network slice; or when multiple network slice types of the at least one network slice type match the service type of the terminal, selecting the type of the to-be-accessed network slice from the multiple network slice types according to the respective priority of each of the multiple network slice types; and wherein sending the information about the to-be-accessed network slice to the access network device, wherein the access network device determines the core network device according to the information about the to-be-accessed network slice, further comprises: sending the network slice ID of the to-be-accessed network slice to the access network device, wherein the network slice ID of the to-be-accessed network slice is used by the access network device to determine the core network device.

7. The method according to claim 1 , wherein obtaining the first network slice information from the access network device comprises: receiving a third message sent by the access network device, wherein the third message comprises the first network slice information.

8. The method according to claim 1 , wherein selecting the information about the to-be-accessed network slice from the first network slice information further comprises: selecting a preset default network slice as the to-be-accessed network slice when the at least one network slice does not comprise a network slice whose type matches a service type of the terminal; or sending an access termination request to the access network device when the at least one network slice does not comprise a network slice whose type matches the service type of the terminal; or obtaining the first network slice information from another access network device when the at least one network slice does not comprise a network slice whose type matches the service type of the terminal.

9. The method according to claim 1 , wherein a network slice type of the at least one network slice type is Cellular Internet of Things (CIoT), Ultra-Reliable communication, or mobile broadband network.

10. A method, comprising: sending, by an access network device, first network slice information to a terminal, wherein the first network slice information is used by a terminal to select a to-be-accessed network slice, wherein the first network slice information comprises information about at least one network slice that can be accessed by an access network device, and wherein a communications network is sliced into a plurality of network slices, and each network slice of the plurality of network slices comprises a set of function entities supporting a communication service of the respective network slice of the plurality of network slices; receiving, by the access network device, information about the to-be-accessed network slice sent by the terminal; and determining, by the access network device, a core network device for the terminal according to the information about the to-be-accessed network slice and second network slice information, and initiating a request to the core network device; wherein the information about the to-be-accessed network slice comprises at least one network slice type; and wherein determining the core network device for the terminal according to the information about the to-be-accessed network slice and the second network slice information comprises: determining, according to a type of the to-be-accessed network slice and the second network slice information, a network slice function entity group identifier corresponding to the type of the to-be-accessed network slice; and determining the core network device for the terminal according to the network slice function entity group identifier and a second preset rule.

11. The method according to claim 10 , wherein determining the core network device according to the information about the to-be-accessed network slice and the second network slice information further comprises: determining a preset default core network device as the core network device when no network slice function entity group identifier corresponding to the type of the to-be-accessed network slice is determined according to the type of the to-be-accessed network slice and the second network slice information; or sending a fourth message to the terminal when no network slice function entity group identifier corresponding to the type of the to-be-accessed network slice is determined according to the type of the to-be-accessed network slice and the second network slice information, wherein the fourth message terminates an access request.

12. The method according to claim 10 , wherein the information about the to-be-accessed network slice further comprises a network slice identity (ID) of the to-be-accessed network slice; and wherein determining the core network device according to the information about the to-be-accessed network slice and the second network slice information comprises: determining, according to the network slice ID of the to-be-accessed network slice and the second network slice information, the network slice function entity group identifier corresponding to the to-be-accessed network slice; and determining the core network device according to the network slice function entity group identifier and a second preset rule.

13. The method according to claim 10 , wherein before sending the first network slice information to the terminal, the method further comprises: obtaining the second network slice information from the core network device, wherein the second network slice information comprises a type and a network slice function entity group identifier of each network slice of the at least one network slice.

14. The method according to claim 13 , wherein the second network slice information further comprises a network slice identity (ID) and a priority of each network slice of the at least one network slice.

15. The method according to claim 10 , wherein before sending the first network slice information to the terminal, the method further comprises: receiving a first message sent by the terminal, wherein the first message indicates a network slice selection capability of the terminal; and wherein sending the first network slice information to the terminal comprises: sending a second message to the terminal according to the first message, wherein the second message comprises the first network slice information.

16. The method according to claim 10 , wherein the second network slice information is received from a second core network device.

17. The method according to claim 16 , wherein the second network slice information includes information about at least one dedicated core network.

18. An apparatus, comprising: a receiver, configured to obtain first network slice information from an access network device, wherein the first network slice information comprises information about at least one network slice and information about at least one network slice type; a processor, configured to select information about a to-be-accessed network slice from the first network slice information, wherein selecting the information about the to-be accessed network slice comprises selecting, from the at least one network slice type, a network slice type which matches a service type of a terminal, as a type of the to-be-accessed network slice; and a transmitter, configured to send the information about the to-be-accessed network slice to the access network device, wherein the information about the to-be-accessed network slice is used by the access network device to determine a core network device, and wherein sending the information about the to-be-accessed network slice to the access network device comprises sending the type of the to-be-accessed network slice to the access network device, wherein the type of the to-be-accessed network slice is used by the access network device to determine the core network device.

19. The apparatus according to claim 18 , wherein the processor is further configured to: determine a to-be-accessed public land mobile network (PLMN) according to a first preset rule; and select, from at least one network slice type supported by the to-be-accessed PLMN, the network slice type which matches a service type of the terminal, as the type of the to-be-accessed network slice.

20. The apparatus according to claim 18 , wherein a network slice type of the at least one network slice type comprises Cellular Internet of Things (CIoT), Ultra-Reliable communication, or mobile broadband network.